Yi et al. [41] investigated the influence of acidity on the ultra- filtration of oil-in-water emulsions and concluded that the clusters of oil retained when used an acidic solution had a larger size compared to ultrafiltration of an alkaline solution. The authors explained that under acidic conditions, there is a reduction of the electrostatic repulsive forces between the clusters, causing them to bind to each other, forming larger agglomerates and thus reducing membrane fouling